Identify Infrastructure Qualities
VMware named five infrastructure qualities: Availability, Manageability, Performance, Recoverability and Security. If you are familiar with other design methodologies you might have encountered other terms, but here i want to describe the VMware terms.

Availability is the ability of a system or service to perform its required function when required. It is usually calculated as a percentage like 99,9%.

Manageability describes the expense of running the system. If you have a huge platform that is managed by a tiny team the operational costs are very low.

Performance is the measure of what is delivered by a system. This accomplishment is usually measured against known standards of speed completeness and speed.

Recoverability describes the ability to return a system or service to a working state. This is usually required after a system failure and repair.

Security is the process of ensuring that services are used in an appropriate way.

Lets take a website for example. To understand how to compare your design against this requirements you could ask yourself:

Availability: Is website up and running?

Manageability: How expensive is it to keep the system up?

Performance: How fast does the webserver responds?

Recoverability: If the server crashes, how fast can it be restored?

Security: Are the customers data safe?

Redundancy and Single Point of Failure
A single point of failure is a component of a system that, if it fails, will cause the entire system to fail. Systems can be made robust bei adding redundancy. A server usually attains internal component redundancy by having multiple hard drives, network connections or power supplies. By having multiple servers attached to a cluster you can archieve server hardware redundancy.

vSphere Fault Tolerance (FT) provides continuous availability for virtual machines by creating a live copy of a virtual machine to another physical host.

Differentiate Business Continuity and Disaster RecoveryBusiness Continuity is focused on avoiding or mitigateing the impact of a risk. (Proactive)Disaster Recovery is focused on how to restore the services after a outage occurs. (Reactive)